ABSTRACT The U.S./Mexico border is a unique macro context for drinking, with increased alcohol availability due to the lower minimum legal drinking age in Mexico of 18 years and an increased number of venues for on premise consumption of alcohol (bars, clubs, restaurants). Previous research has shown that the border population is more at risk for unsafe drinking (binge) and drinking-related problems than the population off the border. Mexican Americans are uniquely exposed to this macro environment by virtue of their location in large numbers in cities on the U.S./Mexico border. This component of the Center will use analyses of archival data (e.g., hospital admissions), ethnographic assessments of drinking venues, and survey methods to examine the association between drinking contexts and problem drinking, and associated drinking problems, including DSM-5 alcohol use disorder (AUD) among Mexican American younger adults (18-39 years of age) living in the California/Mexico border area of Imperial City, El Centro, Heber, and Calexico (hereafter border cities). This sample will be compared to a group of age matched Mexican Americans and non-Hispanic Whites who live away from the border, in the cities of Delano, Madera, Tulare, and Visalia, in the Central Valley of California (hereafter Valley cities). The aims and hypotheses to be tested in this Center component are: Aim 1: Archival data for Mexican Americans in the border cities will show a higher rate of alcohol-related hospital discharges, motor vehicle crashes and emergency room admissions; violent crime rates, violent assault rates; drinking and driving arrest, and higher alcohol outlet density, than data for Mexican Americans and Whites in Valley cities; Aim2: Survey data will show that, a) younger Mexican Americans in the border cities will be more likely to drink in public venues such as bars and clubs than at home and with family than age matched Mexican American and Whites in Valley cities; b) patronage of public drinking venues such as bars and clubs among younger Mexican Americans in the border cities will lead to heavier drinking and more frequent binge drinking; c) patronage of public drinking venues such as bars and clubs will also be associated with younger age (18 to 30), male gender, higher income, drinking with friends (as opposed to family or romantic partner), and higher impulsivity, sensation seeking and risk taking; Aim 3: Survey data will also show that, a) rates of alcohol-related social problems (e.g., with family, job, legal, sexual, aggression), as well as DSM-5 AUD, will be higher among Mexican Americans in the border cities than among age matched Mexican Americans and Whites in Valley cities; and b) higher frequency of drinking in on premise outlets and drinking in Mexico (for residents of border cities) will have an independent effect on alcohol-related social problems and DSM-5 AUD; Aim 4: Unobtrusive systematic observations and semi-structured interviews will be conducted in selected bars in the border cities, in the Valley cities and in Mexicali. It is expected that commercial drinking venues in the Mexican border town of Mexicali, BC (across the border from the selected study cities on the U.S. side), will have riskier operating conditions (e.g., more patrons, more dancing, louder music) as well as lower priced alcohol and later closing times compared to venues in the U.S. border towns and Central Valley towns.